1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright 2021 Google Inc.
4  *
5  * Panel driver for the Samsung ATNA33XC20 panel. This panel can't be handled
6  * by the DRM_PANEL_SIMPLE driver because its power sequencing is non-standard.
7  */
8 
9 #include <linux/backlight.h>
10 #include <linux/delay.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/iopoll.h>
13 #include <linux/module.h>
14 #include <linux/pm_runtime.h>
15 #include <linux/regulator/consumer.h>
16 
17 #include <drm/display/drm_dp_aux_bus.h>
18 #include <drm/display/drm_dp_helper.h>
19 #include <drm/drm_edid.h>
20 #include <drm/drm_panel.h>
21 
22 /* T3 VCC to HPD high is max 200 ms */
23 #define HPD_MAX_MS	200
24 #define HPD_MAX_US	(HPD_MAX_MS * 1000)
25 
26 struct atana33xc20_panel {
27 	struct drm_panel base;
28 	bool prepared;
29 	bool enabled;
30 	bool el3_was_on;
31 
32 	bool no_hpd;
33 	struct gpio_desc *hpd_gpio;
34 
35 	struct regulator *supply;
36 	struct gpio_desc *el_on3_gpio;
37 	struct drm_dp_aux *aux;
38 
39 	struct edid *edid;
40 
41 	ktime_t powered_off_time;
42 	ktime_t powered_on_time;
43 	ktime_t el_on3_off_time;
44 };
45 
46 static inline struct atana33xc20_panel *to_atana33xc20(struct drm_panel *panel)
47 {
48 	return container_of(panel, struct atana33xc20_panel, base);
49 }
50 
51 static void atana33xc20_wait(ktime_t start_ktime, unsigned int min_ms)
52 {
53 	ktime_t now_ktime, min_ktime;
54 
55 	min_ktime = ktime_add(start_ktime, ms_to_ktime(min_ms));
56 	now_ktime = ktime_get_boottime();
57 
58 	if (ktime_before(now_ktime, min_ktime))
59 		msleep(ktime_to_ms(ktime_sub(min_ktime, now_ktime)) + 1);
60 }
61 
62 static int atana33xc20_suspend(struct device *dev)
63 {
64 	struct atana33xc20_panel *p = dev_get_drvdata(dev);
65 	int ret;
66 
67 	/*
68 	 * Note 3 (Example of power off sequence in detail) in spec
69 	 * specifies to wait 150 ms after deasserting EL3_ON before
70 	 * powering off.
71 	 */
72 	if (p->el3_was_on)
73 		atana33xc20_wait(p->el_on3_off_time, 150);
74 
75 	ret = regulator_disable(p->supply);
76 	if (ret)
77 		return ret;
78 	p->powered_off_time = ktime_get_boottime();
79 	p->el3_was_on = false;
80 
81 	return 0;
82 }
83 
84 static int atana33xc20_resume(struct device *dev)
85 {
86 	struct atana33xc20_panel *p = dev_get_drvdata(dev);
87 	int hpd_asserted;
88 	int ret;
89 
90 	/* T12 (Power off time) is min 500 ms */
91 	atana33xc20_wait(p->powered_off_time, 500);
92 
93 	ret = regulator_enable(p->supply);
94 	if (ret)
95 		return ret;
96 	p->powered_on_time = ktime_get_boottime();
97 
98 	if (p->no_hpd) {
99 		msleep(HPD_MAX_MS);
100 		return 0;
101 	}
102 
103 	if (p->hpd_gpio) {
104 		ret = readx_poll_timeout(gpiod_get_value_cansleep, p->hpd_gpio,
105 					 hpd_asserted, hpd_asserted,
106 					 1000, HPD_MAX_US);
107 		if (hpd_asserted < 0)
108 			ret = hpd_asserted;
109 
110 		if (ret)
111 			dev_warn(dev, "Error waiting for HPD GPIO: %d\n", ret);
112 
113 		return ret;
114 	}
115 
116 	if (p->aux->wait_hpd_asserted) {
117 		ret = p->aux->wait_hpd_asserted(p->aux, HPD_MAX_US);
118 
119 		if (ret)
120 			dev_warn(dev, "Controller error waiting for HPD: %d\n", ret);
121 
122 		return ret;
123 	}
124 
125 	/*
126 	 * Note that it's possible that no_hpd is false, hpd_gpio is
127 	 * NULL, and wait_hpd_asserted is NULL. This is because
128 	 * wait_hpd_asserted() is optional even if HPD is hooked up to
129 	 * a dedicated pin on the eDP controller. In this case we just
130 	 * assume that the controller driver will wait for HPD at the
131 	 * right times.
132 	 */
133 	return 0;
134 }
135 
136 static int atana33xc20_disable(struct drm_panel *panel)
137 {
138 	struct atana33xc20_panel *p = to_atana33xc20(panel);
139 
140 	/* Disabling when already disabled is a no-op */
141 	if (!p->enabled)
142 		return 0;
143 
144 	gpiod_set_value_cansleep(p->el_on3_gpio, 0);
145 	p->el_on3_off_time = ktime_get_boottime();
146 	p->enabled = false;
147 
148 	/*
149 	 * Keep track of the fact that EL_ON3 was on but we haven't power
150 	 * cycled yet. This lets us know that "el_on3_off_time" is recent (we
151 	 * don't need to worry about ktime wraparounds) and also makes it
152 	 * obvious if we try to enable again without a power cycle (see the
153 	 * warning in atana33xc20_enable()).
154 	 */
155 	p->el3_was_on = true;
156 
157 	/*
158 	 * Sleeping 20 ms here (after setting the GPIO) avoids a glitch when
159 	 * powering off.
160 	 */
161 	msleep(20);
162 
163 	return 0;
164 }
165 
166 static int atana33xc20_enable(struct drm_panel *panel)
167 {
168 	struct atana33xc20_panel *p = to_atana33xc20(panel);
169 
170 	/* Enabling when already enabled is a no-op */
171 	if (p->enabled)
172 		return 0;
173 
174 	/*
175 	 * Once EL_ON3 drops we absolutely need a power cycle before the next
176 	 * enable or the backlight will never come on again. The code ensures
177 	 * this because disable() is _always_ followed by unprepare() and
178 	 * unprepare() forces a suspend with pm_runtime_put_sync_suspend(),
179 	 * but let's track just to make sure since the requirement is so
180 	 * non-obvious.
181 	 */
182 	if (WARN_ON(p->el3_was_on))
183 		return -EIO;
184 
185 	/*
186 	 * Note 2 (Example of power on sequence in detail) in spec specifies
187 	 * to wait 400 ms after powering on before asserting EL3_on.
188 	 */
189 	atana33xc20_wait(p->powered_on_time, 400);
190 
191 	gpiod_set_value_cansleep(p->el_on3_gpio, 1);
192 	p->enabled = true;
193 
194 	return 0;
195 }
196 
197 static int atana33xc20_unprepare(struct drm_panel *panel)
198 {
199 	struct atana33xc20_panel *p = to_atana33xc20(panel);
200 	int ret;
201 
202 	/* Unpreparing when already unprepared is a no-op */
203 	if (!p->prepared)
204 		return 0;
205 
206 	/*
207 	 * Purposely do a put_sync, don't use autosuspend. The panel's tcon
208 	 * seems to sometimes crash when you stop giving it data and this is
209 	 * the best way to ensure it will come back.
210 	 *
211 	 * NOTE: we still want autosuspend for cases where we only turn on
212 	 * to get the EDID or otherwise send DP AUX commands to the panel.
213 	 */
214 	ret = pm_runtime_put_sync_suspend(panel->dev);
215 	if (ret < 0)
216 		return ret;
217 	p->prepared = false;
218 
219 	return 0;
220 }
221 
222 static int atana33xc20_prepare(struct drm_panel *panel)
223 {
224 	struct atana33xc20_panel *p = to_atana33xc20(panel);
225 	int ret;
226 
227 	/* Preparing when already prepared is a no-op */
228 	if (p->prepared)
229 		return 0;
230 
231 	ret = pm_runtime_get_sync(panel->dev);
232 	if (ret < 0) {
233 		pm_runtime_put_autosuspend(panel->dev);
234 		return ret;
235 	}
236 	p->prepared = true;
237 
238 	return 0;
239 }
240 
241 static int atana33xc20_get_modes(struct drm_panel *panel,
242 				 struct drm_connector *connector)
243 {
244 	struct atana33xc20_panel *p = to_atana33xc20(panel);
245 	struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(panel->dev);
246 	int num = 0;
247 
248 	pm_runtime_get_sync(panel->dev);
249 
250 	if (!p->edid)
251 		p->edid = drm_get_edid(connector, &aux_ep->aux->ddc);
252 	num = drm_add_edid_modes(connector, p->edid);
253 
254 	pm_runtime_mark_last_busy(panel->dev);
255 	pm_runtime_put_autosuspend(panel->dev);
256 
257 	return num;
258 }
259 
260 static const struct drm_panel_funcs atana33xc20_funcs = {
261 	.disable = atana33xc20_disable,
262 	.enable = atana33xc20_enable,
263 	.unprepare = atana33xc20_unprepare,
264 	.prepare = atana33xc20_prepare,
265 	.get_modes = atana33xc20_get_modes,
266 };
267 
268 static void atana33xc20_runtime_disable(void *data)
269 {
270 	pm_runtime_disable(data);
271 }
272 
273 static void atana33xc20_dont_use_autosuspend(void *data)
274 {
275 	pm_runtime_dont_use_autosuspend(data);
276 }
277 
278 static int atana33xc20_probe(struct dp_aux_ep_device *aux_ep)
279 {
280 	struct atana33xc20_panel *panel;
281 	struct device *dev = &aux_ep->dev;
282 	int ret;
283 
284 	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
285 	if (!panel)
286 		return -ENOMEM;
287 	dev_set_drvdata(dev, panel);
288 
289 	panel->aux = aux_ep->aux;
290 
291 	panel->supply = devm_regulator_get(dev, "power");
292 	if (IS_ERR(panel->supply))
293 		return dev_err_probe(dev, PTR_ERR(panel->supply),
294 				     "Failed to get power supply\n");
295 
296 	panel->el_on3_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
297 	if (IS_ERR(panel->el_on3_gpio))
298 		return dev_err_probe(dev, PTR_ERR(panel->el_on3_gpio),
299 				     "Failed to get enable GPIO\n");
300 
301 	panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd");
302 	if (!panel->no_hpd) {
303 		panel->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN);
304 		if (IS_ERR(panel->hpd_gpio))
305 			return dev_err_probe(dev, PTR_ERR(panel->hpd_gpio),
306 					     "Failed to get HPD GPIO\n");
307 	}
308 
309 	pm_runtime_enable(dev);
310 	ret = devm_add_action_or_reset(dev,  atana33xc20_runtime_disable, dev);
311 	if (ret)
312 		return ret;
313 	pm_runtime_set_autosuspend_delay(dev, 2000);
314 	pm_runtime_use_autosuspend(dev);
315 	ret = devm_add_action_or_reset(dev,  atana33xc20_dont_use_autosuspend, dev);
316 	if (ret)
317 		return ret;
318 
319 	drm_panel_init(&panel->base, dev, &atana33xc20_funcs, DRM_MODE_CONNECTOR_eDP);
320 
321 	pm_runtime_get_sync(dev);
322 	ret = drm_panel_dp_aux_backlight(&panel->base, aux_ep->aux);
323 	pm_runtime_mark_last_busy(dev);
324 	pm_runtime_put_autosuspend(dev);
325 	if (ret)
326 		return dev_err_probe(dev, ret,
327 				     "failed to register dp aux backlight\n");
328 
329 	drm_panel_add(&panel->base);
330 
331 	return 0;
332 }
333 
334 static void atana33xc20_remove(struct dp_aux_ep_device *aux_ep)
335 {
336 	struct device *dev = &aux_ep->dev;
337 	struct atana33xc20_panel *panel = dev_get_drvdata(dev);
338 
339 	drm_panel_remove(&panel->base);
340 	drm_panel_disable(&panel->base);
341 	drm_panel_unprepare(&panel->base);
342 
343 	kfree(panel->edid);
344 }
345 
346 static void atana33xc20_shutdown(struct dp_aux_ep_device *aux_ep)
347 {
348 	struct device *dev = &aux_ep->dev;
349 	struct atana33xc20_panel *panel = dev_get_drvdata(dev);
350 
351 	drm_panel_disable(&panel->base);
352 	drm_panel_unprepare(&panel->base);
353 }
354 
355 static const struct of_device_id atana33xc20_dt_match[] = {
356 	{ .compatible = "samsung,atna33xc20", },
357 	{ /* sentinal */ }
358 };
359 MODULE_DEVICE_TABLE(of, atana33xc20_dt_match);
360 
361 static const struct dev_pm_ops atana33xc20_pm_ops = {
362 	SET_RUNTIME_PM_OPS(atana33xc20_suspend, atana33xc20_resume, NULL)
363 	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
364 				pm_runtime_force_resume)
365 };
366 
367 static struct dp_aux_ep_driver atana33xc20_driver = {
368 	.driver = {
369 		.name		= "samsung_atana33xc20",
370 		.of_match_table = atana33xc20_dt_match,
371 		.pm		= &atana33xc20_pm_ops,
372 	},
373 	.probe = atana33xc20_probe,
374 	.remove = atana33xc20_remove,
375 	.shutdown = atana33xc20_shutdown,
376 };
377 
378 static int __init atana33xc20_init(void)
379 {
380 	return dp_aux_dp_driver_register(&atana33xc20_driver);
381 }
382 module_init(atana33xc20_init);
383 
384 static void __exit atana33xc20_exit(void)
385 {
386 	dp_aux_dp_driver_unregister(&atana33xc20_driver);
387 }
388 module_exit(atana33xc20_exit);
389 
390 MODULE_DESCRIPTION("Samsung ATANA33XC20 Panel Driver");
391 MODULE_LICENSE("GPL v2");
392